KarenRei,

Welcome to the fire! Interesting first post. Is your name Japanese or do you work at my favorite money pit? An introduction is always nice.

Thinking about what you wrote:
1. Quicklime: The flocculant idea is good. Using it to pretreat the water before boiling makes sense.

2. pH adjustment (basic): Similar to using bleach to kill the wee little beasties. Wood ashes produce NaOH (sodium hydroxide) which isn't as good as hyperchlorates in this respect. Contact time would need to be pretty long. NaOH solutions can cause permenant damage to eyes and other soft tissues. In this regards they are worse than acid burns. Controlling the dose of NaOH could be a problem. Which bleach-type chemicals the "sniff test" works (if it smells like a swimming pool after sitting several hours it's safe). I just sniffed our pH 10 calibration solution and couldn't smell anything. Perhaps a "slippery test" might work. Basic solutions can cause your skin to feel slick/slippery. Overall, I'd say stay away from this. If you have fire figure out some way of boiling the fire. The poor result control coupled with risk of damage to your mouth/throat makes this a poor choice in my opinion. Sidenote: "Lutefisk" is a Norwegian dish where raw cod is soaked in a NaOH solution for weeks to preserve it.

2. pH acidic: First thought is water-born beasties survive our stomach acid. That right there seems like and arguement against acid-sterilization. On the Walmart Les Stroud "Urban Disaster" DVD Les preserves raw salmon by soaking it in lemon juice at room temperature overnight. He claims this will remain safe to eat for 3-4 days. He states that it must by lemon juices, others aren't acidic enough and also it only works with fish, not chicken (I can't remember if it works with beef).

3. Artifical well: Cool idea, very similar to a refugee-camp sand filtration unit I posted a few weeks ago. For a long term situation involving a family-unit or larger this could make a lot of sense. I like it.

-Blast